FLAME-RETARDANT, LONG-TIME UV-STABILIZED DRAPEABLE SCREEN

Abstract: A difficult to ignite, long-time UV-stabilized drapeable curtain for shading and energy saving, particularly for greenhouses. The curtain is of the kind comprising flexible strips with a thickness less than 100 mu m, which by means of a crochet or weave process and a yarn system forms a continuous product, where the strips constitute at least a part of the surface of the product. At least some of the strips are constituted of light and/or heat reflecting foil strips, e.g. a low emitting metal foil, preferably an AL-foil. The strips are constituted of a halogen or phosphorus bearing plastic film. At least some of the strips are laminated with said foil strips. The yarn system consists, at least partly, of a flame-retardant material, e.g. modacrylic or polyester or a mixture of these.

Description: FL-fl-MERETARDΛNT, LONG-TIME UV-STABILIZED DRAFEABLE SCREEN TECHNICAL AREA The present invention refers to a flameretardant, long-time UV- stabilized drapeable screen for shading and energy saving, particularly for greenhouses, and of the kind comprising flexible strips with a thickness less than 100 μm, which by means of a crochet or weave process and a yarn system form a continuous product, where the strips comprise at least a part of the surface of the product, and at which at least some of the strips comprise light and/or heat reflecting foil strips, e.g. a low emitting metal foil, preferably an AL-foil. BACKGROUND OF THE INVENTION Screens in accordance with above are used for protection of plants outdoors and inside greenhouses, for adjustment of the in- and outflow of radiant energy, so that the plants are protected against too strong sunlight and against too high or too low temperatures. These screens extend vertically and/or horizontally over very large areas, for instance set-ups with up to 30 000 m 2 occur. Such a screen set-up protects large values, since plants may represent a value of about 100 US dollar per square metre. Electrical motors are used to manoeuv¬ re the screens between active and inactive positions. Such a greenhouse screen is described in EP 0109951 and comprises narrow strips of plastic foil, which strips are held together by textile threads and may consist of a polyester foil being metallized on one of its sides. Fires can start in screen systems e.g. because of defects in electrical systems, by repairings such as welding, or when a vehicle is driven inside the greenhouse under a screen system. It has shown that these fires can spread rapidly over large areas via the screens. Such fires may injure people working in the greenhouse and damage the greenhouse in itself. Besides, the vegetation which the screen is meant to protect, is de¬ stroyed. It has also proven hard to modify known plant protection screens, so that they become flameretardant with maintained protection against UV-radiation, during a life expectancy of at least four to five years, without at the same time being very bulky in a drawn aside position. Flameretardant textiles are used in certain environments where one wants to limit the risk of a small local seat of fire being spread over a larger area. Flameretardant yarn textiles are complicated to produce, because of the long way of manufacturing. Such known textiles are not heat reflecting, transmit light to a low extent, are dirt accumulating and water absorbing. Moreover, they do just partly reflect solar radiation. The production cost is high and the width limited. These flameretardant textiles are not usable in connection with greenhouses. Lately, the technical evolution in the area of plastic film has reached so far, that the flameretardancy is satisfied, but the big problem remains, to overcome and slow down the ageing phenomenon, so the user can be guaranteed a definite life of the plastic film. The difficulties have been, that the addition of halogen, in order to improve the flameretardancy, has taken place at the expense of the UV-stability, which was reduced to such an extent that the material was falling to pieces, either already by production or shortly after being exposed to UV- rays. AU-A-79349/91 describes a flameretardant laminate to be used as insulation layer and diffusion barrier within the building sector. This laminate can at its most be used as roller blind, but it does not meet the demands for a greenhouse screen, since the laminate is waterproof, which means that large pools of water may be formed on the horizontal parts of the greenhouse screen, for which water load the screen system is not dimen¬ sioned. Condensation water can be gathered at the underside of the laminate and drip down onto the plants, which then get damaged. Nor does the laminate possess the necessary character¬ istics, i.e. the quality to be able to be draped, which is required for being able to displace the curtain sideways and park it in the form of a narrow package, which steals a minimum of incoming light. Polymers with a chemical structure which reduces the combust¬ ibility have so far been expensive to produce. For plant pro¬ tecting screens, there are also demands on providing products having different degrees of light permeability, which put higher demands on the UV-protection. The demand of certain characteristics, such as the ability of being draped, sideways displaced and easy mounted, in combina¬ tion with demands on low weight and small volume have also resulted in, that the thickness of the materials being part of the curtain, which to a large extent consists of strips, must be very thin. This demand is very hard to combine with, part¬ ly the desired long-time UV-stabilization, which become easier to fulfil the thicker the plastic film of the laminate is (the filter effect), and partly, the demand on being difficult to ignite, where the amount of material influences the self-ex¬ tinguishing ability. A thin material contains a small amount of fire protection means. THE TECHNICAL PROBLEM The purpose of the present invention is to provide a difficult to ignite, long-time UV-stabilized drapeable screen, which is weather-proof and does not present the above described dis¬ advantages, and which can be produced within reasonable costs. THE SOLUTION For this purpose the screens according to the invention are characterized in, that they are formed of a halogen or phospho¬ rus containing plastic film, that at least some of the strips are laminated with said foil strips, and that the yarn system at least partly consists of an flameretardant material, e.g. modacrylic or polyester or a mixture of these. The screen can be divided into longitudinal zones of alterna¬ ting flammable material and flameretardant material. DESCRIPTION OF EMBODIMENT The invention comprises a drapeable screen for plant protec¬ ting purposes, which screen consists of flexible strips, that by means of a crochet or weave process and a yarn system forms a continuous product. At least some of the strips consist of light and/or heat reflecting foil strips, e.g. a low emitting metal foil, prefer¬ ably an AL-foil. The foil strips are supported by plastic film strips consis¬ ting of a halogen or phosphorus containing polymer, such as PVC, PVDC, PCTFE, PVF, PVDF, FEP, PTFE, E/TFE or PETP. Some Of the strips can be transparent, then being considerably more exposed to UV-light than those with AL-foil or similarly laminated strips. These transparent strips are produced in a long-time UV-stabilized polymer with built-in halogen content. At least some of the plastic film strips are laminated with aluminium foil strips. The plastic film strips should have a thickness less than 100 μm, preferably 20-30 μm and the metal foil should have a thickness less than 30 μm, preferably 9 μm. The plastic film and the AL-foil can be joined to each other trough laminating, e.g. by means of a polyurethanebased glue having an addition of phosphated ester. Alternatively the laminate can be produced through co-extruding, extrude lami¬ nating or the like. When the foil screen comprises a large number of flexible plastic film strips, which form a continuous crocheted prod¬ uct, where the plastic film strips constitute at least a part of the surface of the product, the laminate strips can be arranged to extend at least in the longitudinal direction of the product with yarn on at least one of the flat sides of the strips. If the product is woven the laminate strips can be arranged to extend at least in the warp direction of the product, with fillings of yarn in the warp and/or weft direction of the product. In both these cases can the yarn system, at least partly, consist of a material difficult to ignite, e.g. modacrylic or polyester or a mixture of these. Alternatively, the yarn can at least partly consist of a material being difficult to ignite, e.g. halogen bearing polymers. The yarn closeness amounts to 1 - 10 threads per centimetre. This means that liquid drops landing on the curtain are absorbed by the yarn system. All strips in the screen do not need to consist of material being difficult to ignite, but one or more strips of material being difficult to ignite can be alternatingly placed next to one or more strips of flammable material. Practical tests have very unexpectedly shown, that the chosen plastic materials yield such amounts of fire obstructing gases at a fire, that even near by parts of the fabric are protected. Further, the foil curtain can be alternatingly divided into longitudinal zones of flammable material and material difficult to ignite. The strips in the screen can for instance include white light- reflecting strips, transparent strips and strips with metal powder in the polymer. The strips can also be produced of a laminate, comprising partly a non-woven film produced of a material difficult to ignite, and partly a light and/or heat reflecting foil, e.g. a low emitting metal foil, preferably an AL-foil. The invention is not limited to the above described embodi¬ ments, instead more variants are conceivable within the scoop of following claims.

Claims: CLAIMS 1. A difficult to ignite, long-time UV-stabilized drapeable screen for shading and energy saving, particularly for green¬ houses, and of the kind comprising flexible strips with a thickness less than 100 μm, which by means of a crochet or weave process and a yarn system form a continuous product, where the strips constitute at least a part of the surface of the product, and at which at least some of the strips con¬ stitute of light and/or heat reflecting foil strips, e.g. a low emitting metal foil, preferably an AL-foil, c h a r a c t e r i z e d i n, that the strips consist of a halogen or phosphorus bearing plastic film, and at least some of the strips are laminated with said foil strips, and that the yarn system, at least partly, consists of a flameretardant material, e.g. a mod¬ acrylic or polyester or a mixture of these. 2. A screen according to claim 1, c h a r a c t e r i z e d i n, that at least some of the strips are light-transparent and made of a long-time UV-stabilized polymer with built-in halogen content. 3. A screen according to claim 1, c h a r a c t e r i z e d i , that carrier of the foil strips consists of plastic film strips, preferably of a halogen bearing polymer, such as PVC, PVDC, PCTFE, PVF, PVDF, FEP, PTFE or E/TFE. 4. A screen according to claim 3, c h a r a c t e r i z e d i n, that the plastic film strips have a thickness less than 100 μm, preferably 20 - 30 μm and that the metal foil of the laminate has a thickness less than 30 μm, preferably 9 μm. 5. A screen according to claim 2, c h a r a c t e r i z e d i , that the plastic film and the metal foil are connected to each other, e.g. by means of a flameretardant glue. 6. A screen according to claim 1, c h a r a c t e r i z e d i n, that the product is produced by means of warp knit technique, and that laminate strips are arranged to extend at least in the warp and/or weft direction of the product. 7. A screen according to claim 1, c h a r a c t e r i z e d i n, that the product is produced by means of weaving technique, and that the laminate strips are arranged to extend at least in the warp direction, with yarn fillings in the warp and/or weft direction of the product. 8. A screen according to claim 1, c h a r a c t e r i z e d i n, that the yarn, at least partly, consists of a material diffi¬ cult to ignite, e.g. polymers with additions of halogen or phosphorus combinations, glass fibre and the like. 9. A screen according to claim 1, c h a r a c t e r i z e d i n, that one or more laminate strips of a material difficult to ignite are alternately placed next to one or more strips of flammable material. 10. A screen according to claim 1, c h a r a c t e r i z e d i n, that the curtain is alternatingly divided into longitudinal zones of flammable material and flameretardant material. 11. A screen according to claim 1, c h a r a c t e r i z e d i n, that the yarn system consists of yarn made from a splitted oriented plastic film.

Inventors: ANDERSSON HANS, HENNINGSSON GOERAN, ANDERSSON, HANS, HENNINGSSON, GOERAN
Applicants: ANDERSSON HANS, HENNINGSSON GOERAN, SVENSSON LUDVIG INT, ANDERSSON, HANS, HENNINGSSON, GOERAN, LUDVIG SVENSSON INTERNATIONAL B.V.
Application year: 1994
Main classification: A01G9
IPC codes: A01G9, E06B9